Technical Abstract:
Ground beetles are important generalist predators in agricultural landscapes. During 2000-2001 we placed 2 transects of pitfall traps in each of 4 fields of rotated lepidopteran Bt corn and soybean. Sampling was conducted on a weekly basis and traps remained open for a 2-day period. In 2000, we captured 8554 beetles representing 29 species in soybean, and 5877 individuals representing 40 species in cornfields. For 2001, we captured 2827 beetles representing 35 species in soybean, and 5299 individuals representing 36 species in cornfields. Additional sampling will determine if the differences are due to field specific conditions, or whether they are due to the rotation of crop types. Overall, 52 species (39 in soybean and 47 in cornfields) were collected during the 2-year period. Ground beetle populations in both crops and years were characterized by a few dominant species comprising the majority of the catch. For both years and crops, the 5 most abundant species ranged from 75 to 93% of the total catch. These included, Cyclotrachelus alternans, Pterostichus permundus, Poecilus lucublandus, Harpalus pensylvanicus, and Brachinus ovipennis. Further data analysis will ascertain the effect of trap location (e.g. edge versus interior of field) on carabid diversity and abundance. When approved for commercial release, it is anticipated that coleopteran Bt corn will be included in rotation with soybean. Our data is providing background information on ground beetle communities in lepidopteran Bt corn that will be compared with ground beetle communities in coleopteran Bt corn.